Lizards in an Evolutionary Tree

Ecology and Adaptive Radiation of Anoles

Jonathan Losos

Publication Year: 2009

Adaptive radiation, which results when a single ancestral species gives rise to many descendants, each adapted to a different part of the environment, is possibly the single most important source of biological diversity in the living world. One of the best-studied examples involves Caribbean Anolis lizards. With about 400 species, Anolis has played an important role in the development of ecological theory and has become a model system exemplifying the integration of ecological, evolutionary, and behavioral studies to understand evolutionary diversification. This major work, written by one of the best-known investigators of Anolis, reviews and synthesizes an immense literature. Jonathan B. Losos illustrates how different scientific approaches to the questions of adaptation and diversification can be integrated and examines evolutionary and ecological questions of interest to a broad range of biologists.

Cover

Title Page, Other Works in the Series, Copyright, Dedication

Contents

Foreword

Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles is the tenth
volume in the University of California Press’s series on organisms and environments,
whose unifying themes are the diversity of plants and animals, the ways they interact
with each other and with their surroundings, and the implications of those relationships
for science and society. ...

Acknowledgments

My first recollection of an Anolis lizard is from a trip to Miami to visit a great-aunt when
I was about ten. She lived near a park, where I happily chased green anoles, only to be
scared out of my wits by the unexpected appearance of an enormous Cuban Knight
anole (A. equestris). Since then, anoles have been a recurrent theme in my life. ...

Prologue: The Case for Anolis

A green lizard sits on the bank at the edge of a tiny stream near the town of Soroa in
western Cuba. It may appear unassuming, but this is not your ordinary lizard. Its head
is cocked sideways as it peers into the water. Suddenly, it dives into the water, emerging
with a small crayfish in its mouth. ...

1. Evolutionary Biology as Historical Science

One of the great goals of modern science is to understand biological diversity: where it
comes from, how it evolves, and what maintains it. It has fallen to the field of evolutionary
biology to try to answer these questions. In attempting to do so, evolutionary biology
does not fit the everyday view of science in which hypotheses are put forward and subjected
to experimental test. ...

2. Meet the Anoles!

The goal of this chapter is twofold. First, to introduce anoles: what they are, what makes
them unique, and where they occur. Second, to focus on what it is to be an anole species.
How do species differ from one another? How do we tell one from another? How do they
tell one from another? ...

3. Five Anole Faunas, Part One: Greater Antillean Ecomorphs

In this and the next chapter, I break anole diversity into five groups, corresponding
mostly to the anoles of different regions. “Fauna” is used loosely, as two of these faunas
co-occur, and another fauna extends over the majority of the geographic distribution of
these lizards. ...

4. Five Anole Faunas, Part Two: The Other Four

Although they’ve received the lion’s share of research, the ecomorphs are not the whole
anole story. Not even most of it. In fact, less than one anole species in three is a Greater
Antillean ecomorph. In this chapter, I introduce the other elements of anole diversity,
namely the unique (or non-ecomorph) anoles of the Greater Antilles, ...

5. Phylogenetics Evolutionary Inference and Anole Relationships

In the previous two chapters, I have described the distribution and diversity of anoles
with little mention of evolution. Yet, some of the patterns of anole diversity beg, no,
scream for evolutionary analysis. Are members of the same ecomorph class on different
islands closely related? ...

6. Phylogenetic Perspective on the Timing and Biogeography of Anole Evolution

Our current understanding of anole phylogeny (Chapter 5) provides substantial insight
into the evolution of the anole faunas. Throughout the rest of the book, I will frequently
use this knowledge to address questions concerning the origin and maintenance of
anole biodiversity. ...

7. Evolution of Ecomorphological Diversity

Fortunately, the uncertainties about the biogeographic history of Anolis discussed in the
previous chapter have little bearing on understanding of patterns of ecomorphological
radiation and diversification, at least within the West Indies. Phylogenetic information
indicates that for the most part anoles have radiated independently on each island of the
Greater Antilles, ...

8. Cradle to Grave: Anole Life History and Population Biology

Before tackling the question of how anole species interact (Chapter 11), and how such interactions
might drive evolutionary change (Chapter 12), I need to discuss what makes
anoles tick. That is, how do anoles interact with their environment? What happens during
the course of an anole lifetime and why? ...

9. Social Behavior, Sexual Selection, and Sexual Dimorphism

Sexual selection—“the advantage which certain individuals have over others of the same
sex and species solely in respect of reproduction” (Darwin, 1871)—is a topic of great interest
to behavioral and evolutionary biologists. The past 25 years have seen a tremendous
upsurge in interest in sexual selection, ...

10. Habitat Use

A key factor in understanding anole biological diversity is habitat use. Within localities,
coexisting species invariably differ in some aspect of habitat use. Across the landscape,
species replace each other as the environment changes. Through time, habitat use
evolves within clades in predictable ways. ...

11. Ecology and Adaptive Radiation

Adaptive radiation is the evolutionary divergence of members of a clade to adapt to the
environment in a variety of different ways (Simpson, 1953; Givnish, 1997; Schluter,
2000).258 Some of the most spectacular case studies in evolutionary biology are adaptive
radiations. ...

12. Natural Selection and Microevolution

The anole radiation is characterized by divergence of closely related species into different
ecological niches, producing communities composed of ecologically differentiated
species. The theory of adaptive radiation presented in the last chapter posits that this
diversity is the evolutionary result of ecological interactions between initially similar
species. ...

13. Form Function, and Adaptive Radiation

The previous two chapters have focused on the ecological side of adaptive radiation, discussing
how interspecific interactions drive ecological shifts and how natural selection
subsequently leads to evolutionary change. In this chapter, I take the macroevolutionary
perspective: ...

14. Speciation and Geographic Differentiation

Adaptive radiation involves both multiplication of species from a single ancestor and
ecological and phenotypic diversification of these species, with the end result that communities
are composed of multiple species adapted to different niches. The focus of the
last several chapters has been on the second of these two aspects, ...

15. The Evolution of an Adaptive Radiation

In Chapter 11, I defined adaptive radiation as the evolutionary divergence of members of
a clade to adapt to the environment in a variety of different ways and presented three predictions
made by a hypothesis of adaptive radiation: ...

16. The Five Faunas Reconsidered

The Anolis evolutionary pageant exhibits a fundamental duality. On one hand, the
Greater Antillean ecomorphs are renowned for convergence of entire communities,
with the same set of ecomorphs evolving repeatedly. On the other hand, only one of
the other four anole faunas—the anoles of the small islands of the Greater Antilles— ...

17. Are the Anoles Special, and If So, Why?

What’s so great about anoles? Why have I written a whole book about them—and
spent more than 20 years studying them—and why have you read the book? Of course,
they’re attractive and engaging little creatures, with great variety and entertaining
behavior. ...

Afterword

In this section, I present a list of all West Indian anole species and of all mainland
species mentioned in the text. In addition, Figure A.1 presents the complete phylogeny
from Nicholson et al. [2005] that served as the basis for several figures in this book and
was used for all original statistical analyses presented here. ...

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